In 1991 a study showed that human sperm counts had fallen by almost 50 percent in less than 50 years, which increased the cases of male infertility due to lower sperm count.

Toothpaste and sunscreen could be two of the reasons why male infertility is on the rise.

A few years later researchers discovered that common chemicals used in everyday day items such as soap and toothpaste have a negative effect in the male reproductive system – and a new study has found a way of testing the impact of household products on human sperm.
Some chemical substances mimic either male sex hormones or female sex hormones and both interfere with the male reproductive system by slowing down sperm, explains Steve Connor over at the Independent.
The chemicals commonly found in detergents, plastics, toothpaste and even sunscreen also make sperm release enzymes needed to fertilise the egg cell before it reaches it, which may also be a cause of infertility.
In their study the researchers found that these chemicals have what Connor describes as a “cocktail effect”, meaning the presence of one amplifies the effects of others.
“For the first time, we have shown a direct link between exposure to endocrine-disrupting chemicals from industrial products and adverse effects on human sperm function,” said Professor Niels Skakkebaek, of Copenhagen University Hospital in Denmark, to the Independent.
A report from the Centre of Advanced European Studies and Research found that out of 96 common household chemicals, a third had an effect on the protein that controls sperm motility and swimming agility.
“In my opinion, our findings are clearly a concern as some endocrine-disrupting chemicals are possibly more dangerous than previously thought,” said Skkakkebaek. “However, it remains to be seen from forthcoming clinical studies whether our findings may explain reduced couple fertility which is very common in modern society.”
This study is the first one that highlights how common lifestyle or environmental changes affect male fertility.